1. Field of the Invention
This invention relates to a new process for producing s coatings on any substrate by means of a coating composition containing, as binder, a two-component system of a polyisocyanate component and a special isocyanate reactive component.
2. Description of the Prior Art
Two-component coating compositions containing, as binder, a polyisocyanate component in combination with an isocyanate-reactive component, in particular a polyhydroxyl component, are known. They are suitable for the formation of high quality coatings and can he adjusted to produce coatings which are hard, elastic, abrasion resistant and solvent resistant and especially weather resistant.
In accordance with the present invention coating compositions are used in which the binders are based on a two-component system of a polyisocyanate component and an isocyanate-reactive component containing partly or entirely certain secondary polyamines to be described hereinafter. The basic chemical reaction between polyisocyanates and secondary polyamines as used in accordance with the invention is already known from German Offenlegungsschrift 670 812 (=British patent I 190 342), however, according to the teaching of this prior publication said basic reaction is accompanied or immediately followed by a ring forming secondary reaction leading to hydantoins and is, therefore, not used or recommended as hardening reaction for a two-component coating composition.
The systems used in the process according to the invention provide numerous advantages. They are suitable in particular as binders in low solvent or solvent-free coating compositions and enable the coatings to harden rapidly by a chemical cross-linking reaction which takes place at a temperature of at the most 100.degree. C.